Cost Saving Opportunities for Compressors

When making calculations, it is important to apply the overall power requirement concept. All energy consumers that belong to a compressor installation should be accounted for: for example, inlet filters, fans and pumps, dryers and separators. For comparisons between different investment alternatives, the use of comparable values is particularly important. Therefore, the values must be stated in accordance with internationally recognized standards and regulations, for example, as per ISO 1217 Ed.4 -2009.

The working pressure directly affects the power requirement. Higher pressure signifies higher energy consumption: on average 8% more power for 1 bar higher pressure. Increasing the working pressure to compensate for a pressure drop always results in impaired operating economy. Despite this adverse economic effect, increasing compressor pressure is a commonly-used method for overcoming pressure drops caused by an under dimensioned pipe system or clogged filters. In an installation fitted with several filters, especially if they have been operational for a long period of time without being replaced, the pressure drop can be significantly higher and therefore very costly if unattended for long periods of time. In many installations, it is not possible to implement large pressure reductions, but the use of modern regulation equipment allows the pressure to be realistically lowered by 0.5 bar. This represents a power savings of a few percent. This may seem to be insignificant, but considering that the total efficiency of the installation is increased by an equivalent degree, the value of this pressure reduction in terms of actual savings is more readily obvious.

Using a modern master control system, the compressor central plant can be run optimally for different operating situations while enhancing safety and availability. Selecting the right regulation method encourages energy savings through lower system pressure and a better degree of utilization, which is optimized for each machine in the installation. At the same time availability increases, thereby reducing the risk of unplanned downtime. Also, central control allows programming for automatic pressure reduction in the entire system during operation at night and on weekends. As compressed air consumption is seldom constant, the compressor installation should have a flexible design, using a combination of compressors with different capacities and speed controlled motors. Compressors may run with speed control and screw compressors are particularly suited for this, as their flow rate and their power consumption are virtually proportional to their speed.